The prevalence of allergic diseases is on the rise and this increase may in part be associated with industrialization. Among molecules of concern in the xenobiotic mercury (HgCl2) which induces vasculitis and promotes polyclonal IgE production in rats. To determine the effect of HgCl2 on mast cells, mouse bone marrow derived mast cells were exposed to HgCl2 and the effects on degranulation and cytokine secretion measured. HgCl2 was found to directly lead to mast cell degranulation and to secretion of the pro-inflammatory cytokines of IL-4 and TNF- alpha, consistent with the recognition of HgCl2 as a biologically important immunotoxic agent for mast cells.Exploring the role of chemokines in mast cell accumulation at sites of inflammation, only CXC chemokines including IL-8, induced calcium flux in mast cells. Further studies identified IL-8RB (CXCR2) expressed on mast cells, and demonstrated chemotactic responses in human mast cells to IL-8. Thus, CXCR2 receptors appear to play an important role in mast cell recruitment.Exploring mechanisms that might regulate tissue mast cell function, we found that alpha-MSH modulates cyclic AMP levels, thymidine incorporation, and m-RNA levels for selected cytokines in murine mast cells. - Cytokines, chemokines, IL-4, IL-8, TNF-alpha, CXCR2, HgCl2, mast cells, xenobiotics, immunotoxin, degranulation